Penny Cleaning Experiment

Using simple household items from your kitchen pantry, you can clean old, dirty pennies to look like new! This is a great experiment in the classroom or at home.

Combine vinegar and salt in a small bowl. Add the pennies and wait a few minutes. Wipe them off and you will have shiny pennies! When copper atoms combine with oxygen atoms from the air, it forms a molecule called copper oxide. This copper oxide causes the pennies to look dull, dark brown or even green. Copper oxide dissolves in the salt and vinegar mixture (an acid).